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21Symptoms, signs or clinical findings, not elsewhere classified
Symptoms, signs or clinical findings of the nervous system
Symptoms or signs involving the nervous system
MB47Abnormality of tonus or reflex

MB47.9 category

Myotonia

Definition

Slow relaxation of the muscles after voluntary contraction

Also indexed as

Myotonia

Nearby in Abnormality of tonus or reflex

MB47.0Abnormal reflex
MB47.1Abnormal posture
MB47.2Clonus
MB47.3Cramp or spasm
MB47.4Dystonia
MB47.5Fasciculation
MB47.6Meningismus
MB47.7Muscle fibrillation

PreviousMB47.8 — Muscular hypertonia NextMB47.A — Ophthalmoparesis

Browse ICD-11

01Certain infectious or parasitic diseases
02Neoplasms
03Diseases of the blood or blood-forming organs
04Diseases of the immune system
05Endocrine, nutritional or metabolic diseases
06Mental, behavioural or neurodevelopmental disorders
07Sleep-wake disorders
08Diseases of the nervous system
09Diseases of the visual system
10Diseases of the ear or mastoid process
11Diseases of the circulatory system
12Diseases of the respiratory system
13Diseases of the digestive system
14Diseases of the skin
15Diseases of the musculoskeletal system or connective tissue
16Diseases of the genitourinary system
17Conditions related to sexual health
18Pregnancy, childbirth or the puerperium
19Certain conditions originating in the perinatal period
20Developmental anomalies
21Symptoms, signs or clinical findings, not elsewhere classified
22Injury, poisoning or certain other consequences of external causes
23External causes of morbidity or mortality
24Factors influencing health status or contact with health services
25Codes for special purposes
26Supplementary Chapter Traditional Medicine Conditions
VSupplementary section for functioning assessment
XExtension Codes
MA00-MA1YSymptoms, signs or clinical findings of blood, blood-forming organs, or the immune system
MA50-MA6YSymptoms, signs or clinical findings of endocrine, nutritional or metabolic diseases
MA80-MB0YSymptoms, signs or clinical findings of speech, language or voice
MB20-MB2YMental or behavioural symptoms, signs or clinical findings
MB40-MB9YSymptoms, signs or clinical findings of the nervous system
MC10-MC2YSymptoms, signs or clinical findings of the visual system
MC40-MC6YSymptoms, signs or clinical findings of ear or mastoid process
MC80-MC9YSymptoms, signs or clinical findings of the circulatory system
MD10-MD6YSymptoms, signs or clinical findings of the respiratory system
7 more
MB40-MB6YSymptoms or signs involving the nervous system
MB70-MB7YClinical findings in the nervous system
4B4YOther specified diseases of the immune system
MB43Dyssomnia
MB44Abnormalities of gait or mobility
MB45Lack of coordination
MB46Abnormal involuntary movements
MB47Abnormality of tonus or reflex
MB48Dizziness or giddiness
MB49Aura
MB4AApraxia
MB4BSymbolic dysfunctions
8 more
MB47.1Abnormal posture
MB47.2Clonus
MB47.3Cramp or spasm
MB47.4Dystonia
MB47.5Fasciculation
MB47.6Meningismus
MB47.7Muscle fibrillation
MB47.8Muscular hypertonia
MB47.9Myotonia
MB47.AOphthalmoparesis
MB47.BOpisthotonos
MB47.CTendency to fall
MB47.DTetany
4B4YOther specified diseases of the immune system
4B4ZDiseases of the immune system, unspecified
1 more

International Classification of Diseases, Eleventh Revision (ICD-11), World Health Organization (WHO) 2019/2021, https://icd.who.int/browse11. Licensed under Creative Commons Attribution-NoDerivatives 3.0 IGO (CC BY-ND 3.0 IGO).

Release 2026-01. View this entity in the official WHO ICD-11 browser.

This page reproduces WHO classification content for reference. It is not medical advice and must not be used to diagnose or treat. For coding decisions, consult the official release and your national coding guidelines.

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